Our objective is to conduct a detailed, ultrastructural study of the nerve fibers in the organ of Corti and the vestibular sense organs by means of serial sections, and to determine nerve fiber density in Corti's tunnel, habenula perforata and internal auditory canal in both animal and man. The study includes experimental specimens obtained from nerve sections, acoustic trauma, and kanamycin and streptomycin toxicity. This study will aid in the development of an artificial prosthesis for the deaf individual. Our second major objective is to investigate the pathology of endolymphatic hydrops with both scanning and transmission electron microscopes, and to develop a method to prevent the occurrence of experimentally produced hydrops in animals by creating fistula in the saccule, reopening of the blocked site, and use of drugs and chemicals. The inner ear funtion of these animals will be determined by the behavioral conditioning technique. This study will provide information useful for the treatment of Meniere's disease.